“I can’t comment on the (senators’ request). But what I can tell you is we are in full compliance with every regulation in every jurisdiction we are present in,” Thiam told reporters at the bank’s quarterly results news conference on Wednesday.

“When there are sanctions, we are fully compliant with the sanctions, of course, and we have invested a lot of resources in continuously upgrading our ability to monitor.”

Swiss banks practically never comment on individual clients given confidentiality laws that helped make Switzerland the world’s biggest center for managing offshore wealth.

The neutral country has now begun to exchange information on bank clients with foreign tax authorities.

Two Democratic senators have written to U.S.-based Bank of America Corp, JPMorgan Chase and Citibank as well as European groups Barclays, Deutsche Bank, UBS, HSBC and Credit Suisse.

The Trump administration announced sanctions on Russia on April 6, responding to what U.S. intelligence agencies say was Russian interference in the 2016 U.S. election and other adversarial actions by Moscow. Russia denies meddling in the election.

UBS Chief Executive Sergio Ermotti said this week U.S. sanctions on Russians were having only a limited impact on its business. UBS is the world’s biggest wealth manager.

Reporting by Brenna Hughes Neghaiwi, Writing by Michael Shields, Editing by William Maclean